I/O Control
Description
SOUND MIXER INFO
Fill the structure struct mixer
SOUND MIXER VOLUME
Changes the main output volume.
Only the least significant byte is
used to change both left and right
channels.
SOUND MIXER BASS
Changes the bass level. Only the
least significant byte is used to
change both left and right channels.
SOUND MIXER TREBLE
Changes the treble level.
Only
the least significant byte is used to
change both left and right channels.
SOUND MIXER LINE1
Changes the input 1 level.
Only
the least significant byte is used to
change both left and right channels.
SOUND MIXER LINE2
Changes the input 2 level.
SOUND MIXER RECSRC
Reports the supported recording
sources. Each bit of the mask rep-
resents a recording source.
SOUND MIXER RECMASK
Reports the supported recording
channels. Each bit of the mask rep-
resents a recording channel.
SOUND MIXER DEVMASK
Reports the supported channels.
Each bit of the mask represents a
channel.
SOUND MIXER STEREODEVS
Reports the supported stereo chan-
nels. Each bit of the mask reepre-
sents a stereo channel.
Two examples below show how to set and read a mixer parameter using
’ioctl’ functions for the mixer device. MIXER READ() and MIXER WRITE()
are used to specify if you want to read or to write a mixer setting.
...
/* change the input 1 level to 80% */
level = 80;
ioctl(mixer_fd , MIXER_WRITE( SOUND_MIXER_LINE1 ) , &level );
...
...
/* read the level of the input 1 */
ioctl(mixer_fd , MIXER_READ( SOUND_MIXER_LINE1 ) , &level );
printf("input 1 level %u\n" , level );
...
K-Team S.A.
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